This wave has the same absolute Fourier coefficients as saw
but the partial waves are shifted by 90 degree.
That is, it is the Hilbert transform of the saw wave.
The formula is derived from sawComplex.

asymmetry parameter ranging from -1 to 1:
For 0 you obtain the usual triangle.
For -1 you obtain a falling saw tooth starting with its maximum.
For 1 you obtain a rising saw tooth starting with a zero.